Thin kerf saw machinery

ABSTRACT

Thin kerf saw machinery including a saw arbor mounted for rotation above a set of power rollers adapted to transport lumber past the arbor for cutting. A plurality of saw collars are arranged on the arbor in side-by-side relationship, each collar being suspended for free lateral movement along the arbor and adapted to be rotated therewith. Each saw collar supports a circular saw blade fabricated of relatively thin gauge metal for thin kerf sawing. Saw guides are provided for each blade, being retained in control arms positioned adjacent the blades. The saw guides are adapted to exert selective forces on the sides of the saw blades near the gullet line of the blades for independently controlling the position of each blade as it enters the lumber. Each saw guide comprises at least a pair of control pads secured in opposed relationship, one on each side of a corresponding saw blade. The head surfaces of the pads are recessed to form fluidretaining cups which confine a lubricating cushion of fluid adjacent the sides of the saw blades, when rotating. Fluid for filling the lubrication cups and operating the control pads is furnished from a remote source through a network of internal channels in the control arms. In one preferred arrangement, two sets of saw guides are used on each blade, the sets being separated between 60* and 120* along the outer periphery of the blade.

United States Patent Pearson [54] THIN KERF SAW MACHINERY v [72]Inventor: Harry C. Pearson, Beaverton, Oreg. [73] Assignee: PortlandIron Works, Portland,

Oreg.

[22] Filed: Aug. 14, 1970 [21] App]. No.: 63,862

[52] US. Cl. ..83/824, 83/169, 83/676 [51] Int. Cl. ..B27b 5/34 [58]Field of Search ..143/37, 56, 160, 1601-1, 164, 143/157 C, 157 G, 158;83/20l.l5, 169, 676; 308/D1G. 1

[56] References Cited UNITED STATES PATENTS 113,698 4/1871 Sherman et al..143/56 995,991 6/1911 Trout ..143/37 R 3,202,189 8/1965 Pearson....143/37 R 3,479,097 11/1969 McLauchlan et ai ....83/2O1. l 5 X3,593,763 7/1971 Neild .83/201.l5 X 843,336 2/1907 Garland ..143/160 R3,540,334 ll/l970 McLauchlan ..83/169 X 3,465,794 9/ 1969 McLauchlan eta1 ..83/20L15 X Primary Examiner-Andrew R. Juhasz AssistantExaminer-James F. Coan Attomey-Kolisch & Hartwell [57] ABSTRACT Thinkerf saw machinery including a saw arbor mounted for rotation above aset of power rollers adapted to transport lumber past the arbor forcutting. A plurality of saw collars are arranged on the arbor inside-by-side relationship, each collar being suspended for free lateralmovement along the arbor and adapted to be rotated therewith. Each sawcollar supports a circular saw blade fabricated of relatively thin gaugemetal for thin kerf sawing. Sa'w guides are provided for each blade,being retained in control arms positioned adjacent the blades. The sawguides are adapted to exert selective forces on the sides of the sawblades near the gullet line of the blades for independently controllingthe position of each blade as it enters the lumber. Each saw guidecomprises at least a pair of control pads secured in opposedrelationship, one on each side of a corresponding saw blade. The headsurfaces of the pads are recessed to form fluidretaining cups whichconfine a lubricating cushion of fluid adjacent the sides of the sawblades, when rotating. Fluid for filling the lubrication tmps andoperating the control pads is fumished from a remote source through anetwork of internal channels in the control arms. In one preferredarrangement, two sets of saw guides a e on a h bl e 11 i M 1992'sseparated between 60 and 120 along the outer periphery of the blade.

14 Claims, 6 Drawing Figures 'PATENTEDHI1V28 I912 WU 1 or 4 3703.915

CPecl rs on INVENTOR BY KM HM Harri;

PATENTEDmwz i 12 1 3.703.915

SHEET 2 UF 4 INVENTOR BY KM Hm BACKGROUND OF THE INVENTION The presentinvention relates to saw machinery especially designed for use in thelumber industry. More particularly, the invention relates to machineryfor precisely controlling the cutting path of a saw blade adapted forcutting a thin kerf.

Conventional saw machines used in the lumber industry, and particularlyhigh production machines adapted for making battery cuts of moving cantsor flitches, are equipped with saw blades formed of heavy gauge metaland, therefore, are adapted to cut wide kerfs. These machines usuallyinclude a plurality of circular saw blades, each blade being mounted ona separate saw collar, with the collars being suspended side-by-sideupon a rotatable arbor. Various means are utilized to attain the desiredspacing between blades and to control the cutting path of the respectiveblades. In general, however, the control systems for heavy gauge sawsmerely adjust the spacing between the saw collars of adjacent blades andrely upon the stiffness of the blades to maintain satisfactory alignmentof the cutting path of the blades.

To further minimize deviations of the blade from the desired cuttingline, the heavy gauge saw blades are usually tensioned. Tensioning of acircular saw blade is a conventional operation which consists oftreating the metal of the blade so that the inner periphery of thefinished blade has a residual tension greater than the outer peripheryof the blade. The purpose of tensioning the blade is to compensate forthe effect of centrifugal force when the blade is rotating. Withouttensioning, the outer periphery of the blade has a tendency to increasein circumference when rotating. Such loose blades tend to snake whencutting.

In view of the rising cost of wood in recent years, attempts have beenmade to replace heavy gauge saws with thin saws to reduce kerf wastageand increase the amount of usable lumber which can be obtained from agiven log. Furthermore, saw arrangements have been designed for moreaccurately controlling the cutting line of the saw blades so that roughcuts of lumber can be made closer to the desired size of the finishedlumber. This eliminates other wastage in the cutting of a given log.

Some of the thin kerf saw arrangements utilize multiple band sawsarranged for battery cutting. However, such systems are generally slowand not practical for use in our domestic lumber industry.

Other thin kerf sawing arrangements, utilizing setups of thin circularsaw blades, can be generally characterized as including saw collarsdesigned to float in gang fashion on the rotating saw arbor. The systemsutilize control pads which contact the saw blades near the outerperiphery of the blades. The control pads must be placed in thatposition due to a lack of stiflness in the thin saw blades, and due to adifficulty in properly tensioning the thinner blades.

One sawing arrangement utilizing thin kerf circular blades is describedin U. S. Pat. No. 3,285,302 to Thrasher which is an improvement over thethick kerf saw arrangements previously used in the lumber industry.However, certain undesirable features are present in the Thrashersystem. In particular, the system discloses the use of blade contactingcontrol pads which are subject to wear and which result in heating ofthe saw blades. In addition, the saw arbor and contact pads of Thrasherare arranged below the work piece. Consequently, the blade controlsystem is constantly showered with saw dust and other debris and issubject to excessive fouling.

Furthermore, the Thrasher system uses only a single reference point forsaw blade control, i.e., at the first saw line. The cutting lines of theother saw blades are all established with respect to the next adjacentsaw blade. Therefore, snaking in one saw cut can be reflected into thesaw line of the adjacent saw blades.

SUMMARY OF THE INVENTION Accordingly, it is an object'of the inventionto provide improved saw machinery, satisfactorily utilizing saw bladesof smaller thickness than was heretofore possible.

It is another object of the invention to provide high production sawmachinery for accurately making battery cuts of moving cants or flitchesof lumber at increased operating speeds.

A further object is to provide saw machinery where it is not criticalthat saw blades used in the machinery be tensioned.

It is yet another object of the invention to provide saw machineryincluding saw guides that provide a fluid cushion on either side of eachsaw blade.

A related object is the provision of such machinery which furtherincludes a unique fluid supply system for the saw guides.

It is a further object of the invention to provide saw blade controlmeans wherein at least two' sets of saw guides are provided for each sawblade. These are located in a predetermined position with respect to theblade to minimize the formation of standing waves in the saw blade whenrotating.

It is yet a further object of the invention to provide a saw bladecontrol system which includes one control pad for each saw blade thatindependently establishes a desired saw line for that blade, andincludes another self-adjusting control pad for aligning the saw bladewith respect to the reference point.

These and other objects of the invention are attained by saw machinerywhich includes a saw arbor mounted for rotation above a set of rollersadapted to transport flitches past the arbor for cutting. A plurality ofsaw collars are arranged on the arbor in sideby-side relationship, eachcollar being mounted on the arbor for free lateral movement with respectthereto. Each collar supports a circular saw blade fabricated ofrelatively thin gauge metal. Saw guides are provided on both sides ofeach saw blade, being located near the gullet line of the blade foraccurately determining the cutting line of each saw blade. Each sawguide includes a pair of control pads mounted in opposed relationship toeach other, one on each side of the saw blade, for controlling theposition of the blade as it cuts the lumber.

The control pads are retained within cylinders formed in the ends ofcontrol or support arms suspended between the saw blades from a supportshaft. Fluid for operating the control pads is supplied to the cylindersthrough an arrangement of internal fluid passages within the supportarms. The head surface of each control pad is recessed to form afluid-retaining cup adjacent the saw blade. An opening is providedthrough each control pad for delivery of fluid, under pressure, into thecup to form a fluid cushion between the control pad and the side of thesaw blade. In one preferred embodiment of the saw machinery, two'or moresets of saw guides. are provided for each saw blade, the sets of guidesbeing spaced-apart along the outer periphery of the saw blade atanangular distance ranging between 60 and 120, the angular distance notbeing divisible by an'integral number into 360, to provide control ofstanding waves as well be described.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of theinvention will become apparent from the following detailed descriptionof the invention taken in conjunction with drawings, wherein:

FIG. 1 is a side elevation view in section of saw machinery designed inaccordance with the invention;

FIG. 2 is a top cross-sectional view, of the saw machinery;

FIG. 3 is a partial sectional view, along the line 33 of FIG. 1 and onan enlarged scale, showing an arrangementof cylinders and control padsused in controlling multiple saw blades on an overhead arbor;

FIG. 4 is a perspective view of a saw arbor and saw collar arrangementsuitable for use with the embodiment described, 1

FIG. 5 is a sectional view through one side of the saw collar shown inFIG. 4; and

FIG. 6 is a perspective simplified view of a disk which has beeninserted to explain the control forces exerted on the saw blade by thecontrol apparatus of the inventIOn.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, andparticularly to FIGS. 1 and'2, one embodiment of the invention is shownin the form of saw machinery 10. adapted for battery cutting of cants orflitches of lumber. Saw machinery 10 generally comprises a framework 11from which are supported a feed roller system 12, a rotatablesaw arborl4 and a saw blade control means 15.

Saw arbor 14 is supported for rotation in bearings 18, 19 (FIG. 2) anddriven by a motor, not shown, through drive belts 22. Other drivesystems, such as a directly coupled motor, could, of course, be used.Movement is in a counterclockwise direction as shown in FIG. 1. Aplurality of saw blades 16 are supported for rotation with the saw arborin a manner to be explained.

The lumber feed roller system is adapted for feeding cants or flitchesinto the saw blades and for transferring the cut lumber away. from thesaw. The system generally includes a plurality of lower rollers 23 theaccompanying a set of their ends to a shaft 28 supported by bearings,not shown, in framework 11. 31 are provided, having one end fixedlysecured to the shaft 28, slightly offset from arms 27, and the other endsecured to a connecting pin 32. Pin 32 is universally connected to shaft34 of a fluid-operated ram such as a hydraulic ram 35, secured toframework 11. Ram 35 is supplied with fluid under pressure, from asource not shown, to adjust the'height of rollers 26 and thereby varypressure exerted on the workpiece. Under normal operating conditionsrollers 26 are adjusted to a height which permits the weight of therollers to ride onthe flitches for starotatably supported in bearings 24in the framework 1 l 1. Rollers 23 are adapted to be driven byconventional means, not shown, in a clockwise direction as shown in FIG.1 to transport flitches past the saw arbor. The feed system furtherincludes a plurality of pressure rollers 26 supported above the feedrollers for stabilizing the cants during cutting.

As seen in FIG. 1, each roller 26 is suspended for free rotation from apair of arms, such as arm 27, joumaled at the ends of the roller. Arms27 are fixedly secured at bilizing them. If desired, rollers 26 can bepositively driven in synchronism with rollers 23 although this is notnecessary. I

Referring to FIGS. 4 and 5, each saw blade 16 is secured to arbor 14 bymeans of a saw collar 37. The saw blades are fabricated for cutting thinkerfs. The term thin kerf commonly might refer to kerfs of less than0.130, inches in width. The saw collars are mounted side-by-side asshown in FIGS. 4-5. A single saw blade and saw collar will be described,it being understood that the other corresponding elements are similarthereto.

Each saw blade 16 is formed with a circular center opening of suitablesize to fit snugly over a hub 38 of collar 37, in contact with the sideof a lip 39 upstanding from the hub. A retaining ring 41 is provided,also having an inside diameter adapted to fit over hub portion 38. Thesaw blade 16 is positioned between lip 39 and retaining ring 41 andsecured to the hub by screws 42, located in suitable openings in theretaining ring and saw blade and engaging threaded holes in the lipportron.

Each collar is secured to the saw arbor for rotation therewith by athree-point suspension which permits free lateral movement of the sawblade along the arbor during rotation.

Further explaining, arbor I4 is a splined shaft, having nine keyways 44formed therein equally spaced around the periphery of the shaft. Eachsaw collar is joined to three elongate key-support arms 45 presented atthe inner surface of the hub, spaced at intervals around the peripherythereof. Each arm 45 is set transverse to the cutting plane of the sawblades and has a recessed bottom surface adapted to receive acorresponding key 46. Each key 46 is secured to its support arm byscrews 48 and is adapted to fit within a corresponding keyway of thespline.

The key support arms are sufficiently long to provide good verticalstability to the saw blades. Suitable tolerance is provided between thekeys and the keyways of the arbor to permit free lateral movement of thesaw collars along the arbor, even when rotating.

Am 45 are adapted to fit under the collars of adjacent saw blades in anested configuration when the saw collars are closely spaced. To permitsuch nesting, the inside diameter of the hubs of the saw collars is madesubstantially larger than the outside diameter of the saw arbor. Thenested collar arrangement is illustrated in FIG. 4 where adjacent keysupport arms 45a, 45b and 450 are shown, each being associated with adifferent saw collar and blade.

The nested saw collar configuration is advantageous in that it enablesclose positioning of the saw blade for cutting thin strips of lumber,while providing good vertical stability of the individual saw blades.

The position of each of the saw blades along a desired saw line isestablished and maintained by a novel control system particularlyillustrated in FIGS. 1-3. The control system includes means forindependently controlling the saw line of each saw blade by exertingnecessary control forces on the blade just before it enters theworkpiece. The method of control, explained in detail hereinafter, is asignificant improvement over the prior art.

While machinery has been described with a control system fornonshiftable saws, obviously a similar control system could be used withadjustable saws.

Referring now to FIG. 2, a plurality of control arms 51 are shown, thearms also being referred to herein as support arms, each saw blade beinglocated between two control arms. The control armsare supported inside-by side relationship on a shaft 53 extending between the sides offramework 11. Predetermined lateral spacing of arms 51 on shaft 53 isestablished by spacer rings 54 between the control arms. Shaft 53 isfixedly secured to the framework 11, being attached on one end to asleeve 55 welded to the framework 11 and being retained at the other endwithin a hollow collar 56 received in a corresponding hole throughframework 11. The collar end of shaft 53 is formed with a threaded outerportion of reduced diameter adapted to extend through the center ofcollar 56 to receiver washer 57 and retaining nut 58.

With retaining nut 58 tightened on shaft 53, collar 56 exerts lateralpressure upon the contacting surfaces of arms 51 and spacer rings 54 tohold the arms firmly in position between the saw blades. However, uponloosening of nut 58, arms 51 can be pivoted upwardly to a rest positionaway from the saw blades. This provides sufficient clearance for anynecessary maintenance of the saw blades and collars, as well asmaintenance of the control means retained within the control arms.

The range of pivotal movement of the control arms, when free, isdetermined by an arrangement of reference surfaces on the shaft 53 andan adjustable stop bolt provided on each of the control arms. Referringto FIG. 1, shaft 53 is modified or recessed along its length whereby afirst cam surface 61 and a second cam surface 62 offset therefrom aredefined. Stop bolt 64 is adjustably retained in a threaded hole throughthe back of the control arm, being held in the desired position by locknut 65. As shown, the control arms, when free, can be lowered until theend of bolt 64 contacts cam surface 61. Likewise, the control arms canbe pivoted in a counterclockwise direction as viewed in FIG. 1, untilbolt 64 contacts cam surface 62.

By adjusting the stop bolts associated with each control arm, therelative position of the arm and the saw arbor can be adjusted.Preferably, the lower surfaces of the control arms are locatedrelatively close to the upper surface of the workpiece so that the sawblades are controlled at a point near their entry into the workpiece.However, to avoid damage thereto, the control arms should never bepositioned lower than the bottom surface of pressure roller 26.

With the arbor overhead and the saw blades rotating in acounterclockwise direction as viewed in FIG. 1, the

cutting teeth of the saw blades and the lumber are moving in the samedirection, in contrast to the usual operation of circular saw blades.However, by positioning the lumber so that the saw blade extendssubstantially below its lower surface, and the angle of departure (b ofthe teeth from the lumber is 30 or greater, the tendency of the sawblades to kick the workpiece is avoided.

The location of the control arms above the workpiece, which is permittedonly by the use of the overhead arbor, avoids a build-up of sawdust andother debris on the control arms and between the saw blades and thecontrol pads. Consequently, the arrangement disclosed is a significantimprovement over prior art systems which are subject to constant foulingfrom debris. I

Saw guides are provided including control pads located on both sides ofeach saw blade in generally opposed relationship. Each of the controlpads includes a fluid-operated control head adapted to fit closelyagainst the saw blade when the blade is at rest. With the bladesrotating the control pads are operated, under a unique fluid pressuresystem, to exert control forces on the saw blades. The control pads areretained within cylindrical bores formed in the ends of the controlarms; and fluid to actuate thecontrol pads is supplied through a uniquearrangement of internal channels fonned in shaft 53 and the controlarms. The blade influencing heads of the control pads are recessed toform fluid-retaining cups adjacent the saw blades.

Upon activation of the control system, fluid is supplied to the cupsunder pressure to form a fluid bearing between each pad and itscorresponding saw blade. The fluid bearing acts to lubricate the sawblade, when rotating, and to prevent wear of the control pad. However,the fluid bearing is sufficiently thin that effective control forces canbe exerted upon the sides of the saw blades by the pads to maintainaccurate alignment of the saw blade even when cutting through knots orother obstructions in the lumber.

Referring now to FIGS. 1, 2 and 3, one preferred arrangement of sawguides is explained in detail. With the exception of the control arms atthe ends of the saw arbor, identical saw guides are confined within eachof the control arms. Consequently, only a single control arm will beexplained, it being understood that the other corresponding control armsare identical thereto. The control arms and associated saw guides at theends of the arbor are separately described.

Each control arm includes an upper portion (FIG. 1), having an uppercylindrical bore 71 formed therein, and a lower portion 73 having alower cylindrical bore 74 formed therein. An expansion slot 76 isprovided in the periphery of the upper portion to facilitate theinstallation of a sleeve in bore 71. A capscrew 77 is provided in theupper portion, secured in a threaded hole extending through theexpansion slot for firmly holding sleeve 80 within the opening. Insimilar fashion, expansion slot 78 and capscrew 79 are provided in thelower portion of the control arm for the installation and retention ofan identical sleeve 80 within the opening 74.

Referring now to FIG. 3, the sleeve 80 in each cylindrical bore includesa ring portion 82 forming an inner wall or lining for the cylinder. Aflange or lip 83 is attached to one edge of the ring portion, having adiameter greater than the ring portion for engaging the surface of thecontrol arm around the periphery of bore 71. A dividing wall 85 extendsacross the sleeve, separating the latter into upper and lower chambersas viewed in FIG. 3. A raised annular plug 86 is formed in the center ofthe dividing wall on the lip side, having an annular groove 87 whichextends around the periphery of the plug. A small hole 89 is formedthrough the center of wall 85 and plug 86 to adrriit fluid therethrough.Another small hole 90 is formed in the periphery of the ring portion ofthe sleeve for admitting fluid into the interior of the sleeve from afluid channel 95 within the control arm.

A fixed control pad 91 is retained within sleeve 80 on the lip side ofwall 85, and a self-adjusting control pad 92 is retained within thesleeve on the other side of the wall. Both control pads are formed of arelatively soft material, such as nylon, soft metal, or other suitablematerial. The control pads are of modified disk shape and have adiameter slightly less than the inside diameter of the ring of sleeve80.

Pad 91 is formed with a circular opening 88 in the center thereof,adapted to fit over the periphery of plug 86 for mounting of the pad. Around sealing ring 96, formed of rubber or composition, is providedbetween the pad and plug 86, seated in groove 87. The outer face or head97 of the control pad is formed with a recessed portion 98 in the centerthereof forming a fluid-retaining cup when the pad contacts the side ofthe saw blade. When the saw blade is rotating the slight leakage offluid from the cup serves to lubricate the saw blade.

- Control pad 92 is movably retained within the sleeve and defines anextensible fluid chamber 101 between wall 85 and the back surface 99 ofthe pad. A relatively small hole, 100 is formed through the center ofpad 92 to permit flow of fluid from chamber 101 to a recessedfluid-retaining cup 102 formed in the front face or head 104 of the pad.Aseal-retaining groove 105 is formed around the outer periphery of pad92 and a collapsible sealing ring 107 is retained therein to maintainfluid pressure within chamber 101.

Sealing ring 107 includes a base portion 109 and a lip ll-attached toone edge of the base portion. When fluid pressure is exerted from abovethe seal, lip 110 is forced into sealing engagement with the surface ofring 80. However, upon release of fluid pressure, lip 110 can be forcedback into the groove so that pad 92 is free from contact with the sawblade. This enables the control arms to be easily removed from betweenthe saw blades for servicing of the saw machinery.

Referring now to FIG. 1, fluid channels 95 in the control arm areconnected with a groove 1 formed in the length of shaft 53. The groovein shaft 53 is located to communicate with channels 95 when the controlarms are lowered into a control position. However, when the control armsare raised, such communication is interrupted. Groove 115 receives fluidfrom a reservoir through a fluid line, not shown, which is connected tothe groove at the end of the support shaft.

The control arms located at the ends of the arbor each include only onecontrol pad; with the control arm at one end of the arbor being providedwith a fixed control pad 91 and the control arm at the opposite end of 8the arbor being provided with a self-adjusting control pad 92.

It should be apparent that each of the fixed control pads 91 establishesan independent reference point or cutting line for the saw bladeassociated therewith, as determined by the positioning of the controlarms on shaft 53.

Without fluid pressure in channels and chambers 101, the control padsmay rest in contact with the saw blades. However, when the saws are tobe operated, fluid under pressure is supplied to the chambers, andthrough holes 89, to the fluid retaining cups in the faces of thecontrol pads.

Holes 89, 100 are of suitable diameter to permit a build-up of pressurein the cups sufiicient to force the self-adjusting control pad a slightdistance away from the saw blade, whereby a lubricating cushion of fluidis maintained on each side of the blade. This prevents excessive wear ofthe control pads. However, due to the difference in the fluid contactingarea between the front of the control pad 92 and the rear of the controlpad, a force is exerted by pad 92 that maintains the saw blade againstthe fluid bearing of pad 91 and in alignment with the desired cuttingline. Should the blade strike a foreign object or knot in the lumber,any tendency of the blade to deviate from the cutting line is minimizedby the forces exerted on the sides of the saw blade by the control pads.

While a single set of saw guides located near the gullet line of the sawblade produces an operable result, it is preferred that multiple sets ofsaw guides be utilized for control purposes. In the embodiment shown,two sets of saw guides are provided, being mounted on a single controlarm. This arrangement is advantageous since the upper and lower sawguides are maintained in good alignment even if the'saw guides arepivoted away from the saw blade for maintenance and then returned.Furthermore, the radial spacing of the respective sets of saw guides ismaintained. The sets of saw guides are illustrated spaced-apart near thegullet line of the rotating blade at an angular distance ofapproximately 66. During experimental usage, this has been found to be aparticularly effective control arrangement.

it is believed that the advantages which result from the use of multiplesets of saw guides can best be explained, theoretically, by comparingthe motion'of a rotating circular saw blade, supported as in the presentsaw machinery, to the gyroscopic motion exhibited by a similarlysuspended rotating disk.

Referring particularly to FIG. 6, a disk is illustrated supported upon ashaft, rotating in the direction indicated by the arrow R. With the diskrotating, it is known that a force exerted moving the front edge of thedisk to the left, as represented by the arrow A, will create a reactionforce upon the disk, represented by the arrow B, causing the top of thedisk to move to the right. Similarly, a force exerted moving the frontedge of the disk to the right, will create a reaction force upon thedisk causing the top of the disk to move to the left.

In view of the above, it should be apparent that the use of a single setof saw guides, located at the front of a circular saw blade, would notresult in the best possible control of the saw blade. Thus, any forceexerted upon the front of the blade to correct a deviation from thecutting line would cause the top of the saw blade to tilt in thedirection of the deviation. Therefore, in order to control the deviationof the saw blade, it would be necessary to overcome both the forcecausing the original deviation of the saw blade and the reaction forceon the blade caused by the corrective force of the saw guide.

However, referring again to FIG. 6, it is known that a force moving thetop of the disk to the left, as represented by the arrow C, will createa reaction force upon the disk, represented by the arrow D, causing theback of the disk to move to the right and the front of the disk to moveto the left. In similar fashion, a force moving the top of the disk tothe right, will create an opposite reaction force upon the disk.

Accordingly, a second set of saw guides located at or near the top ofthe saw blade can be used effectively to overcome the reaction forcesupon the blade that result from the saw guides at the front of theblade. For example, assuming that the front of the saw blade deviatesfrom the cutting line to the right, it is then necessary for the controlpad at the front of the blade to exert a corrective force moving thefront of the saw blade back to the left. This corrective force causes areaction force, tending to tilt the saw blade to the right. However, ifa second set of saw guides is used at the top of the saw blade, a secondcorrective force is applied to the top of the blade, preventing thetilt. At the same time, the reaction force resulting from the secondcorrective force causes the front of the saw blade to move to the left,in the desired direction to correct the original deviation of the blade.Furthermore, the magnitude of the corrective force applied at the top ofthe blade is equal to the reaction force tending to tilt the blade.Accordingly, the second set of saw guides serves to compensate for anyreaction force on the saw blade that occurs due to the saw guides at thefront of the blade.

For ideal compensation, the second set of saw guides should be spaced atan angular distance of 90 from the first set of saw guides. However, ithas been observed that spacing of the saw guides in that positionpermits what I will refer to as standing waves to occur in the rotatingsaw blade. The phenomena resulting in the build-up of standing waves insolid bodies due to vibration are well-known. In the particular case ofa rotating saw blade, it has been observed that with multiple sets ofsaw guides angularly spaced along the saw blade at intervals of 60 or90, the build-up of standing waves is pronounced. The presence of suchstanding waves is exhibited in the form of a distortion or bending ofthe edge of the saw blade transverse to the cutting line. The maximumdistortion of the saw blade occurs midway between the saw guides andresults in a blade distortion commonly known in the lumber industry asblade snaking.

It has been found that the occurrence of standing waves in a rotatingsaw blade can be eliminated by using multiple sets of saw guides locatedat angular spacings that are not divisible by an integral number into360. In particular, angular spacings of 60 and 90 should be avoided.During experimental operations, it has been observed that the use ofmultiple sets of saw guides angularly spaced along the saw blade bydistances falling between 66 and 82 prevents the occurrence of standingwaves and adequately compensates for the reaction forces that occur onthe saw blade.

It is claimed and desired to secure by Letters Patent:

1. Saw machinery including a saw arbor adapted for rotation and acircular saw blade mounted on the arbor, and guide means for controllingthe cutting line of the saw blade, said guide means comprising first andsecond control pads, each of said control pads having a head forexerting control force upon the saw blade, said head having a recessedportion for confining fluid to provide a fluid film between the head andthe saw blade when rotating,

means for supporting said first control pad with the head thereofadjacent one side of said saw blade proximate the gullet line of saidblade, said means comprising a support arm having said first control padmounted thereon with the pad fixedly located with respect to saidsupport arm at a reference point that establishes the cutting line ofthe saw blade,

means for supporting said second control pad with the head thereofadjacent the other side of said saw blade opposite said first controlpad proximate the gullet line of said blade, said means comprisinganother support arm having means defining a cylindrical bore, saidsecond control pad being mounted for reciprocal movement within saidbore with such reciprocal movement changing the position of the head ofsaid second control pad with respect to the head of said first controlpad,

means for moving at least said second control pad with respect to theassociated support means, and means for supplying fluid to the recessedportions of the heads of the control pads.

2. Saw machinery as claimed in claim 1, wherein a seal is providedbetween the second control pad and the cylindrical bore said secondcontrol pad and said bore define an internal chamber within said othersupport arm, and wherein means is provided for supplying fluid to saidchamber whereby a pressure of fluid is maintained within said chamber.

3. Saw machinery as claimed in claim 2, wherein said second control padis formed with a groove about the periphery thereof, and said sealincludes an annular base member fitting closely within the groove and anannular lip flexibly secured to an edge of said base member forming areleasable pressure seal between said control pad and said cylindricalbore maintaining fluid under pressure within said chamber.

4. Saw machinery as claimed in claim I, wherein said support arms areformed with internal channels therein, and the means for supplying fluidto the recessed portions of the heads of the control pads comprisesmeans in the control pads connecting their recessed portions with theinternal channels formed in their respective support arms.

5. Saw machinery including first and second spaced circular saw blades,

an elongate support arm having a cylindrical bore formed through one endof said arm and an internal channel formed within said arm communicatingwith said bore,

means mounting said arm on said saw machinery with its said one enddisposed between said first and second saw blades,

a cylindrical sleeve retained within said bore including a wall dividingsaid sleeve into first and second chambers opening, respectively, towardsaid first and second saw blades, said sleeve having an opening formedtherein adapted to communicate with said internal channel,

a first control pad mounted within said first chamber adapted to exertcontrol force upon said first saw blade, and

a second control pad mounted within said second chamber adapted to exertcontrol force upon said second saw blade.

6. Saw machinery as claimed in claim 5, wherein said first controlpad isretained at a fixed location within said first chamber to define acutting line for said first saw blade, and said second control pad isreciprocably retained within said second chamber for providing controlforce to said second saw blade in response to fluid pressure within saidsecond chamber,

7. Saw machinery as claimed in claim 6, wherein said second control padis formed with a groove about the outer periphery thereof, a seal memberis mounted within said groove including an annular base fitting closelywithin said groove and an annular lip flexibly secured to said baseforming a releasable pressure seal between said control pad and saidsleeve.

8. Saw machinery as claimed in claim further in cluding means forsupplying fluid from said internal channel to form a fluid film betweeneach control pad and its associated saw blade.

9. Saw machinery comprising a framework,

an elongate saw arbor rotatably supported on said framework having atleast one circular saw blade mounted thereon, v

a support arm disposed on one side of the saw blade and a first controlpad mounted on and fixedly located with respect to said support arm at areference point that establishes the cutting line of the saw blade,

another support arm disposed on the opposite side of the saw blade and asecond control pad mounted on said other support arm disposed oppositesaid first control pad, the mounting for said second control pad on saidother support arm accommodating reciprocal movement of the control padwith respect to said other support arm in a direction substantiallynormal to the plane of the saw blade and including an expansiblefluid-retaining chamber behind the control pad which expands withmovement of the control pad toward the saw blade, and

means for admitting fluid under pressure to said expansible chamber.

10. The apparatus of claim 9, wherein said second control pad has arecessed head facing the saw blade for confining fluid to provide afluid film between the head and saw blade, and said pad has a passagetherein connecting said expansible chamber and the recess of the headfor supplying fluid from said chamber to the recess of said head.

1 I. Saw machinery including first and second laterally spaced circularsaw blades,

- an elongate support arm supported on said saw machinery with an endportion thereof located between said saw blades, means at said endportion of said arm defining one chamber facing one of said saw bladesand another oppositely facing chamber facing the other of said sawblades 1 a first control pad mounted within said one chamber exerting acontrol force on said first saw blade,

a second control pad mounted within said other chamber exerting acontrol force on said second saw blade,

said first control pad being retained at a fixed location within saidfirst chamber to define a cutting line for said first saw blade and saidsecond control pad being reciprocably retained within said secondchamber for providing a yieldable control force to said second sawblade.

12. The saw machinery of claim 11, wherein said support arm has achannel defined therein adapted to be connected to a supply of fluidunder pressure, and wherein means connects said channel to said otherchamber to admit fluid under pressure into said other chamber with saidfluid exerting a pressure on said second control pad.

13. The saw machinery of claim 12, wherein each control pad has arecessed head for confining fluid, to provide a fluid film between thehead and the saw blade that the pad containing the head controls, andwherein each pad includes means connecting the channel defined in saidarm with the recessed head of the pad.

14. Saw machinery including a saw arbor and a saw blade mounted on saidarbor,

an elongate support arm mounted in said machinery having an end adjacentsaid saw blade and means at said end of said support arm defining achamber facing said saw blade, control pad reciprocably mounted withinsaid chamber for exerting a controlling force on the saw blade, thereciprocal movement being normal to the plane of the blade, said padhaving a recessed head on a side thereof facing the saw blade forconfining fluid to provide a fluid film between the head and the sawblade when the saw blade is rotating, a passage in said control padconnecting the recessed head with said chamber in a region of thechamber located on the opposite side of the pad from said head, andmeans for introducing fluid under pressure to said region of saidchamber to produce a pressure fluid against said pad urging the sameagainst said saw blade and also to introduce fluid to the recess of saidhead through said passage in the control pad.

1. Saw machinery including a saw arbor adapted for rotation and acircular saw blade mounted on the arbor, and guide means for controllingthe cutting line of the saw blade, said guide means comprising first andsecond control pads, each of said control pads having a head forexerting control force upon the saw blade, said head having a recessedportion for confining fluid to provide a fluid film between the head andthe saw blade when rotating, means for supporting said first control padwith the head thereof adjacent one side of said saw blade proximate thegullet line of said blade, said means comprising a support arm havingsaid first control pad mounted thereon with the pad fixedly located withrespect to said support arm at a reference point that establishes thecutting line of the saw blade, means for supporting said second controlpad with the head thereof adjacent the other side of said saw bladeopposite said first control pad proximate the gullet line of said blade,said means comprising another support arm having means defining acylindrical bore, said second control pad being mounted for reciprocalmovement within said bore with such reciprocal movement changing theposition of the head of said second control pad with respect to the headof said first control pad, means for moving at least said second controlpad with respect to the associated support means, and means forsupplying fluid to the recessed portions of the heads of the controlpads.
 2. Saw machinery as claimed in claim 1, wherein a seal is providedbetween the second control pad and the cylindrical bore said secondcontrol pad and said bore define an internal chamber within said othersupport arm, and wherein means is provided for supplying fluid to saidchamber whereby a pressure of fluid is maintained within said chamber.3. Saw machinery as claimed in claim 2, wherein said second control padis formed with a groove about the periphery thereof, and said sealincludes an annular base member fitting closely within the groove and anannular lip flexibly secured to an edge of said base member forming areleasable pressure seal between said control pad and said cylindricalbore maintaining fluid under pressure within said chamber.
 4. Sawmachinery as claimed in claim 1, wherein said support arms are formedwith internal channels therein, and the means for supplying fluid to therecessed portions of the heads of the control pads comprises means inthe control pads connecting their recessed portions with the internalchannels formed in their respective support arms.
 5. Saw machineryincluding first and second spaced circular saw blades, an elongatesupport arm having a cylindrical bore formed through one end of said armand an internal channel formed within said arm communicating with saidbore, means mounting said arm on said saw machinery with its said oneend disposed between said first and second saw blades, a cylindricalsleeve retained within said bore including a wall dividing said sleeveinto first and second chambers opening, respectively, toward said firstand second saw blades, said sleeve having an opening formed thereinadapted to communicate with said internal channel, a first control padmounted within said first chamber adapted to exert control force uponsaid first saw blade, and a second control pad mounted within saidsecond chamber adapted to exert control force upon said second sawblade.
 6. Saw machinery as claimed in claim 5, wherein said firstcontrol pad is retained at a fixed location within said first chamber todefine a cuttinG line for said first saw blade, and said second controlpad is reciprocably retained within said second chamber for providingcontrol force to said second saw blade in response to fluid pressurewithin said second chamber.
 7. Saw machinery as claimed in claim 6,wherein said second control pad is formed with a groove about the outerperiphery thereof, a seal member is mounted within said groove includingan annular base fitting closely within said groove and an annular lipflexibly secured to said base forming a releasable pressure seal betweensaid control pad and said sleeve.
 8. Saw machinery as claimed in claim 5further including means for supplying fluid from said internal channelto form a fluid film between each control pad and its associated sawblade.
 9. Saw machinery comprising a framework, an elongate saw arborrotatably supported on said framework having at least one circular sawblade mounted thereon, a support arm disposed on one side of the sawblade and a first control pad mounted on and fixedly located withrespect to said support arm at a reference point that establishes thecutting line of the saw blade, another support arm disposed on theopposite side of the saw blade and a second control pad mounted on saidother support arm disposed opposite said first control pad, the mountingfor said second control pad on said other support arm accommodatingreciprocal movement of the control pad with respect to said othersupport arm in a direction substantially normal to the plane of the sawblade and including an expansible fluid-retaining chamber behind thecontrol pad which expands with movement of the control pad toward thesaw blade, and means for admitting fluid under pressure to saidexpansible chamber.
 10. The apparatus of claim 9, wherein said secondcontrol pad has a recessed head facing the saw blade for confining fluidto provide a fluid film between the head and saw blade, and said pad hasa passage therein connecting said expansible chamber and the recess ofthe head for supplying fluid from said chamber to the recess of saidhead.
 11. Saw machinery including first and second laterally spacedcircular saw blades, an elongate support arm supported on said sawmachinery with an end portion thereof located between said saw blades,means at said end portion of said arm defining one chamber facing one ofsaid saw blades and another oppositely facing chamber facing the otherof said saw blades, a first control pad mounted within said one chamberexerting a control force on said first saw blade, a second control padmounted within said other chamber exerting a control force on saidsecond saw blade, said first control pad being retained at a fixedlocation within said first chamber to define a cutting line for saidfirst saw blade and said second control pad being reciprocably retainedwithin said second chamber for providing a yieldable control force tosaid second saw blade.
 12. The saw machinery of claim 11, wherein saidsupport arm has a channel defined therein adapted to be connected to asupply of fluid under pressure, and wherein means connects said channelto said other chamber to admit fluid under pressure into said otherchamber with said fluid exerting a pressure on said second control pad.13. The saw machinery of claim 12, wherein each control pad has arecessed head for confining fluid, to provide a fluid film between thehead and the saw blade that the pad containing the head controls, andwherein each pad includes means connecting the channel defined in saidarm with the recessed head of the pad.
 14. Saw machinery including a sawarbor and a saw blade mounted on said arbor, an elongate support armmounted in said machinery having an end adjacent said saw blade andmeans at said end of said support arm defining a chamber facing said sawblade, a control pad reciprocably mounted within said chamber forexerting a controlling force on the saw blade, the reciprocal movementbeing normal to the plane of the blade, said pad having a recessed headon a side thereof facing the saw blade for confining fluid to provide afluid film between the head and the saw blade when the saw blade isrotating, a passage in said control pad connecting the recessed headwith said chamber in a region of the chamber located on the oppositeside of the pad from said head, and means for introducing fluid underpressure to said region of said chamber to produce a pressure fluidagainst said pad urging the same against said saw blade and also tointroduce fluid to the recess of said head through said passage in thecontrol pad.